• Journal of radiological science and technology
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• v.32 no.2
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• pp.177-182
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• 2009

Purpose : This study presents the optimization of flip angle (FA) to obtain higher contrast to noise ratio (CNR) and lower specific absorption rate (SAR). Materials and Method : T1-weighted images of the cerebrum of brain were obtained from 50$^\circ$ to 130$^\circ$ FA with 10$^\circ$ interval. Signal to noise ratios (SNRs) were calculated for white matter (WM), gray matter (GM), and background noise. The proper FA was analyzed by T-test statistics and Kruskal-wallis analysis using R1 = 1- exp ($\frac{-TR}{T1}$) and Ernst angle cos $\theta$ = exp ($\frac{-TR}{T1}$). Results : The SNR of WM at 130$^\circ$ FA is approximately 1.6 times higher than the SNR of WM at 50$^\circ$. The SNR of GM at 130$^\circ$ FA is approximately 1.9 times higher than the SNR of GM at 50$^\circ$. Although the SNRs of WM and GM showed similar trends with the change of FA values, the slowdown point of decrease after linear fitting were different. While the SNR of WM started decreasing at 120$^\circ$ FA, the SNR of GM started decreasing at less than 110$^\circ$. The highest SNRs of WM and GM were obtained at 130$^\circ$ FA. The highest CNRs, however, were obtained at 80$^\circ$ FA. Conclusion : Although SNR increased with the change of FA values from 50$^\circ$ to 130$^\circ$ at 3T SE T1WI, CNR was higher at 80$^\circ$ FA than at the usually used 90$^\circ$ FA. In addition, the SAR was decreased by using smaller FA. The CNR can be increased by using this optimized FA at 3T MR SE T1WI.

• The Korean Journal of Food And Nutrition
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• v.15 no.1
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• pp.36-41
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• 2002

The aim of this study was to assess the antitoxic compounds, flavanones(Leachianone A=LA and Sophoraflavanone G=SFG), from Sophora flavescens(S. flavescens). We investigated the possibility of antitoxicity of LA and SFG against NIH 3T3 fibroblasts cell lines using calorimetric MTT[3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl -2H-tetra-azolium bromide] assay. The results were as follows : After cadmium was treated against NIH 3T3 cell lines, we determined IC$\_$50/. Accordingly we have examined the detoxification effects of S. flavescens, LA and SFG under cadmium IC$\_$50/=12.5$\mu$M and was carried out to observe morphological changes by the light microscopic study In NIH 3T3 cells, Sophora flavescens, LA, SFG and LA + SFG showed inhibitory effects on the cytotoxicity of cadmium and these detoxication effects increased in proportion to the concentration of these drugs. These results suggest that LA and SFG from S. flavescens retain a potential antitoxic activity.

• Korean Journal of Environmental Biology
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• v.40 no.3
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• pp.275-280
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• 2022

Suspended solids play an important role in the growth and survival of aquatic organisms. The marine zooplankton species tested in this study were Tigriopus west (Copepoda) and Haustorioides koreanus (Amphipoda) sampled from the intertidal zone, including Artemia nauplii(Branchiopoda) hatched from cysts. The study design included six concentrations (0, 50, 100, 250, 500, and 1,000mg L^-1) of the suspended test particles assayed in triplicate. Experimental cultures in 500 mL-round polycarbonate bottles were subsampled after 96 h to count dead zooplankton. The culture bottles were agitated at 4 RPM on a rotating wheel at 23℃ and 30 PSU. The survival rates of Artemia nauplii and T. west were not affected by suspended solid concentrations higher than 50.0 mg L^-1, whereas the survival rate of H. koreanus decreased with increasing concentrations (p<0.05). In conclusion, H. koreanus and T. west, which were continuously exposed to suspended solid concentrations higher than 50.0 mg L^-1, were affected by low-intensity ecological stress. However, in the case of H. koreanus, a concentration of 50.0 mg L^-1 may be considered to be the limit of tolerance to suspended solids, suggesting that the number of individuals who eventually die will increase if continuously exposed.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.34-34
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• 2020

희귀식물(LC)인 낙지다리(Penthorum chinense Pursh.)는 '수택란', '차근채'로 불리며 약용으로 사용되어 왔으나, 최근 하천개수 및 습지매립 등으로 자생지가 파괴되어 개체수가 급감하고 있다. 따라서 본 연구는 낙지다리의 종 보존 및 활용을 위하여 종자의 최적발아조건을 확인하고자 수행하였다. 종자는 2017년 국립백두대간수목원에서 수집되어 연구에 사용되기 전까지 건조 상태(15℃, 15% RH)로 시드뱅크(-20℃, 40% RH)에 저장하고 있었다. 종자의 최적발아조건을 확인하기 위하여, 항온과 변온 66조건에서 발아율과 최종발아율의 50%가 발아하는데 소요되는 일 수(T₅₀)를 조사하였으며, 생리적 휴면 타파를 위해서 GA₃(20~1000 mg·L^-1) 처리 후 발아율과 T₅₀을 조사하였다. 그리고 GA₃ 처리에 따른 유묘 생장에 대한 GA₃의 영향을 확인하기 위하여 종자 치상 30일 후 유근·아 생장에 대한 영향을 조사하였다. 낙지다리 종자는 항온보다 변온에서 발아율 증가와 T₅₀ 감소를 보였다. 특히 낮/밤의 온도 차가 11~25℃일 때, 85%이상의 발아율을 보였고, 그 이상의 온도차이가 나면 발아율은 감소하는 경향을 보였다. T₅₀은 온도차가 증가할수록 감소하여, 발아가 균일하며 빨라지는 것을 확인 할 수 있었다. 또한 GA₃ 처리시 생리적 휴면 타파가 진행되어 발아율(79.8%~100%)과 발아속도가 증가(T₅₀ 감소)함을 확인하였으나, GA₃ 100mg·L^-1 이상의 농도에서는 무처리(21.2m)에 비하여 유근의 길이 생장을 0.11~6.88mm로 지연시켰다.

• Horticultural Science & Technology
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• v.18 no.3
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• pp.327-333
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• 2000

This experiment was conducted to determine the effect of priming duration and temperature on germinability of vegetable seeds. Priming chemicals were -0.50 MPa PEG 8000 for carrot, 50 mM $K_3PO_4$ for lettuce, 200 mM $KH_2PO_4$ for onion, and 100 mM $Ca(NO_3)_2$ for Welsh onion seeds. Priming temperature varied from $10^{\circ}C$ to $25^{\circ}C$, and priming duration varied from 12 hours to 5 days depending on crops. Percent germination of carrot seeds was significantly affected by the seed treatment and priming temperature. Priming at $20^{\circ}C$ for 3 days was most effective in reducing number of days to attain 50% of the final germination percentage (T50) and mean number of days to germination (MDG). Radicle protrusion in the priming solution was as high as 14% when primed at $20^{\circ}C$ for 4 days. Percent germination of lettuce seeds was affected significantly by the seed treatment and priming duration. Priming lettuce seeds at $20^{\circ}C$ for 2 days increased percent germination and shortened T50 and MDG without radicle protrusion. Percent germination of onion seeds was affected significantly by the seed treatment, priming duration, and temperature. Priming at either $10^{\circ}C$ or $15^{\circ}C$ for 3, 4, or 5 days did not affect percent germination of onion seeds, but was effective in reducing T50 and MDG. Decline in percent germination of onion seeds was precipitous as the length of priming duration increased from 3 to 5 days. Percent germination of welsh onion seeds was not affected by the priming duration and temperature. Priming at $15^{\circ}C$ for 4 days was most effective in reducing T50 and MDG, increased in duration of priming at $15^{\circ}C$ or $20^{\circ}C$ increased radicle protrusion.

• Journal of Mushroom
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• v.12 no.1
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• pp.8-11
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• 2014

In this study, we attempted to find substitute materials for bottle cultivation of Pleurotus ostreatus such as poplar sawdust. The chemical characters of mixture substrates with albasia, poplar and douglas fir sawdust were not different significantly. Incubation period was shorter in the albasia sawdust 50% treatment than in the albasia sawdust 100% treatment. The yield and bio-efficiency of fruit-body albasia sawdust 50% treatment, were similar to the poplar 100% and douglas fir 100% treatment. Therefore, it was suggested that albasia sawdust 50% treatment could be substituted for poplar and douglas fir sawdust for bottle cultivation of P. ostreatus.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.263-266
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• 1999

Tobacco (Nicotiana tabacum L. ‘KF109’) seeds were primed in polyethylene glycol 6000 (PEG 6000) solutions to determine a) what osmotic potential of the solution would be optimal for priming, i.e., critical potential level for preventing germination, and b) what temperature and duration would be the most effective in priming. The germination was completely prevented below -0.8 MPa of PEG 6000, that indicates a optimum water potential for seed priming. Seeds were primed for 0, 1, 2, 3, 5, 10 and 15 days at 15, 20 and $25^{\circ}C$, respectively, under the-0.8 MPa PEG 6000 solution to find out the most effective temperature and duration for priming. The effectiveness of priming, particularly in germination speed, was observed more distinctly when the primed seeds were germinated at 15$^{\circ}C$ than 2 5$^{\circ}C$. The greatest reduction of the time to 50% germination (T/sob 50/) was when the seeds were primed at $25^{\circ}C$. The reduction rate of the $T_{50}$ was rapid when primed from 1 day to 8 days and then slowed down in the seeds primed for longer than 8 days. The time from 10 to 90% germination ( $T_{10-90}$ increased in the primed seeds for longer than 8 days which showed the reversed effect of synchronous germination. However, $T_{50}$ was reduced continuously in the seeds even primed over 8 days. Thus, the optimum condition for tobacco seeds priming with PEG 6000 solution was -0.8 MPa in osmotic potential of the solution at $25^{\circ}C$ for 8 days.ays.

• Food Science of Animal Resources
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• v.41 no.1
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• pp.45-58
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• 2021

This study investigated the dietary effect of total mixed ration (TMR) based on high roughage content on the growth performance, carcass characteristics, and meat quality of Hanwoo steers. Twenty-four Hanwoo steers (average body weight, 195.3±4.7 kg; age, 8.5 mon) were randomly allocated to three experimental groups according to forage and concentrate ratio (DM basis): 25:75 (control), 50:50 (T50), and 70:30 (T70). Productivity in the fattening period and final body weight were significantly higher in the control. Average daily gain and feed conversion ratio were the same among treatments. Serum parameters, cholesterol, blood urea nitrogen, and total protein were higher in the control. Carcass weight was comparable in the control and T50 but feeding more roughage was significantly correlated with a higher intramuscular fat. Shear strength and drip loss were higher while n-6/n-3 was lower in T70 compared to the other groups. However, meat color was not significantly different among treatments. In terms of free amino acid contents, glutamic acid and glycine were higher in the control than T50 and T70. Overall, feeding Hanwoo steers with high forage content TMR had the lowest n-6/n-3 ratio of fatty acid content but highest intramuscular fat, shear strength, and drip loss. High forage content TMR is the best feed for Hanwoo steers that gives more benefits for human health and consumption but also provides the best meat grade and quality, which is important in the beef market in Korea.

• Structural Engineering and Mechanics
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• v.53 no.6
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• pp.1271-1286
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• 2015

Recently, US NRC revised fracture toughness requirements as 10CFR50.61a to reduce the conservatism of 10CFR50.61. However, unlike previous studies relating to the initial regulation, structural integrity evaluations based on the alternative regulation are not sufficient. In the present study, PTS and P-T limit curve evaluations were carried out by using both regulations and resulting data were compared. With regard to the PTS evaluation, the results obtained from the alternative requirements were satisfied with the criterion whereas those obtained from the initial requirements did not meet the criterion. Also, with regard to the P-T limit curve evaluation, operating margin by 10CFR50.61a was greater than that by 10CFR50.61.

• YAKHAK HOEJI
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• v.34 no.3
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• pp.192-198
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• 1990

Three sugar glass dispersions of sulfamerazine were prepared using dextrose, galactose and sucrose as the carriers, with the ratio of the drug to the carrier was 1:9. The chemical stability of sulfamerazine in the glass dispersion system was studied using TLC. TLC revealed no additional spot and there was good correspondence with the Sulfamerazine itself. While time required to dissolve 50%($T_{50%}$) of sulfamerazine powder was 390 min that of dextrose glass dispersion system was 1.5 min. and galactose system was 4.0 min. in distilled water. 23) $T_{50%}$ of physical mixture with dextrose, galactose and sucrose were 26.4 min., 26.5 min., and 26.0 min. respectively in distilled water. $T_{50%}$ of control was 54 min. and those of all of the glass dispersion systems were within 1 min. in 0.1N HCl. The dissolution rates of sulfamerazine from sugar glass dispersion system in distilled water was greater than that in 0.1N HCl.